Chemical Hazards and their Adverse Health Effects

Chemicals affect our everyday lives. They are used to produce almost everything we use, from paper and plastics to medicines and food to gasoline, steel, and electronic equipment. More than 70,000 chemicals are used regularly around the world. Some occur naturally in the earth or atmosphere, others are synthetic, or human-made.

When we use and dispose of them properly, they may enhance our quality of life. But when we use or dispose of them improperly, they can have harmful effects on humans, plants, and animals. Water can be an important source of chemical hazards.

What is hazardous waste?

Even when used properly, many chemicals can still harm human health and the environment. When these hazardous substances are thrown away, they become hazardous waste. Hazardous waste is most often a by-product of a manufacturing process - material left after products are made.

Some hazardous wastes come from our homes: our garbage can include such hazardous wastes as old batteries, bug spray cans, and paint thinner. Regardless of the source, unless we dispose of hazardous waste properly, it can create health risks for people and damage the environment.

What kinds of hazardous waste are there?

Most hazardous waste is identified by one or more of its dangerous properties or characteristics: corrosive, ignitable, reactive, or toxic.

• Corrosive - A corrosive material can destroy a substance. For example, most acids are corrosives that can eat through metal, burn skin on contact, and give off vapors that burn the eyes.

• Ignitable - An ignitable material can burst into flames easily. It poses a fire hazard; can irritate the skin, eyes, and lungs; and may give off harmful vapors. Gasoline, paint, and furniture polish are ignitable.

• Reactive - A reactive material can explode or create poisonous gas when combined with other chemicals. For example, chlorine bleach and ammonia are reactive and create a poisonous gas when they come into contact with each other.

• Toxic - Toxic materials or substances can poison people and other life. Toxic substances can cause illness and even death if swallowed or absorbed through the skin. Pesticides, weed killers, and many household cleaners are toxic.

How can hazardous waste affect us?

When hazardous wastes are released in the air, water, or on the land they can spread, contaminating even more of the environment and posing greater threats to our health. For example, when rain falls on soil at a waste site, it can carry hazardous waste deeper into the ground and the underlying groundwater. A hazardous substance can cause injury or death to a person, plant, or animal if:

• A large amount is released at one time

• A small amount is released many times at the same place

• The substance does not become diluted

• The substance is very toxic (for example, arsenic).

Humans, plants, and animals can be exposed to hazardous substances through inhalation, ingestion, or dermal exposure.

• Inhalation - we can breathe vapors from hazardous liquids or even from contaminated water while taking a shower.

• Ingestion - we can eat fish, fruits and vegetables, or meat that has been contaminated through exposure to hazardous substances. Probably the most common type of exposure is drinking contaminated water.

• Dermal exposure - a substance can come into direct contact with and be absorbed by our skin.